(Comparative Anatomy and Physiology Brought Up to Date--continued, Part 9D)Potential reactions to information
in this paper: Part 1 (cont.)

Rationalizations in Response to the Evolutionary and Hunter-Gatherer Evidence for Omnivorous Diets

Similar to rationalizations offered in reaction to the comparative anatomy evidence for omnivorous adaptation are the following--sometimes more sophisticated--diversionary ploys that may be offered in response to evolutionary and hunter-gatherer evidence.

RATIONALIZATION:What happened back in the Paleolithic age doesn't really matter. We are different people today, in most every way. The diet of the Paleolithic is irrelevant nowadays given the new conditions we live under that must be coped with.

REPLY:Genetically, we are in fact quite closely similar to the hunter-gatherers of the late Paleolithic era. As Eaton et al. [1988, p. 740] note:

Accordingly, it appears that the [human] gene pool has changed little since anatomically modern humans, Homo sapiens sapiens, became widespread about 35,000 years ago and that, from a genetic standpoint, current humans are still late Paleolithic preagricultural hunter-gatherers.

Because of the close (nearly identical) genetic similarity, the diet of Paleolithic times is relevant. Of course we do live under different circumstances, and we adapt accordingly. However, for evolutionary adaptation to be reflected in the gene pool is generally believed to require a very long time--considerably longer, in any event, to produce more than but minimal changes since the time humans took up agriculture and ceased to be exclusive hunter-gatherers (roughly 10,000 years ago; much less for some groups).

RATIONALIZATION:Evolution is concerned with reproductive success, not longevity. An evolutionary diet does not have to provide excellent health, it only has to be good enough to allow one to survive to reproduce. We can improve on evolution, and raw/veg*n diets are a good example thereof. After all, veg*ns live longer than non-veg*ns!

REPLY:

Proposing veg*n diet as an improvement on evolution is a reversal of the logic implicit in veg*n naturalism claims. The above is probably one of the major defenses to be employed by raw/veg*n advocates. First, the claim that we can improve on evolution can be restated as, "We can improve on nature." This rationalization neatly reverses the logic that underlies the bogus but popular claim that raw/veg*n diets are best because they (allegedly) are "most natural" for humans. Anyone who uses the naturalism argument for raw/veg*n diets, but then uses the rationalization above, is being inconsistent.

The claim that raw/veg*n diets are an improvement on nature has little if any real supporting evidence. There are some vegan diet advocates who are aware of the evolutionary and paleoanthropological evidence and honestly admit that vegan diets are not natural. That aside, the claim that veg*n diets are an improvement over evolution is simply speculative. There is certainly ample evidence to suggest that conventional veg*n diets are better than SAD/SWD diets, but no comparisons of veg*ns with hunter-gatherers or other groups today attempting to follow modern versions of an evolutionary diet such as Paleodiet advocates in clinical trials or epidemiological studies. As previously discussed in this paper, to make an implicit equation of the SAD/SWD with evolutionary diets just because both are omnivorous is fallacious. Hence one cannot say that veg*n diets are "healthier" than natural, evolutionary, hunter-gatherer-type diets.

There is extensive anecdotal evidence for raw vegan diets that indicates long-term success stories are rare. On the other hand, anecdotal evidence for conventional vegan diets suggests they are much more successful, in the long-run, than raw vegan diets. This doesn't tell us anything about how such diets would fare against evolutionary diets, however--long-term longitudinal studies of conventional veg*ns are lacking.

The claim conveniently avoids the failure-to-thrive issue. Another obvious issue here as discussed earlier--or at least that is obvious to those ex-vegetarians who have made concerted, intelligent attempts at vegan diets (even conventional vegan diets, i.e., including grains/legumes) and who have failed--is the problem of "failure to thrive." (See earlier section on Drawbacks to Relying Exclusively on Clinical Studies of Diet, starting about one-third to one-half the way down the page, for a discussion of how mechanisms of built-in structural bias operate in the vegan community to minimize/prevent awareness of failure to thrive or its relevance.) This is an issue that, by and large, has yet to be faced squarely and honestly by very many in the vegetarian movement (including most of its scientifically oriented advocates). Thus, claims that vegan diet is an improvement over evolution ring hollow when so much remains unknown about actual rates of failure to thrive, and when the question continues to be largely glossed over by all but a very few in the vegetarian movement.

Evolutionary discordance. An important additional consideration here is the concept of "evolutionary discordance"--that is, negative repercussions as a result of behavior contrary to the organism's genetic design.

Our genetic makeup reflects an evolutionary compromise between multiple, competing selective pressures. The organism's physiology is therefore a reflection of adaptations (to such multiple pressures) that must function simultaneously in concert, and that mutually and intimately affect one another. As a result, the body, as determined by its genetic "blueprint," is a densely interwoven mesh of interdependent physiological systems that are very tightly integrated.

Disregarding the genetic dietary range may cause negative repercussions due to the physiological interdependencies determined by evolution. The range of dietary adaptation supported by our genetic code is also the result of multiple selection pressures with their resulting physiological interdependencies. The problem with straying too far from the behavior/environment (which includes diet) that the body has adapted to genetically is that an alteration in one facet is likely to cause unanticipated repercussions, via the body's tightly woven and interdependent physiological systems. Attempted manipulation of one factor or attribute in the mix may occur at the expense of others, because of the multiple evolutionary selection pressures that have resulted in the particular "balance" of physiological factors that act as "constraints" on each other in the organism's functioning.

Despite the fact that evolution may not (in the case of any given species) select for longevity, therefore, it does select for highly integrated physiological designs where the component systems mutually constrain each other. This places limits on how much the environment/behavior/diet of the organism can be changed without negative consequences to the majority of individuals in the gene pool. (Excepting of course, those individuals with the requisite genetic polymorphisms--variations--to benefit from such changes.)

It may be possible to alter one's diet significantly, i.e., to adopt an "evolutionarily discordant" diet, and to see short-term, positive results. A good (if extreme) example is provided by vegan forms of fruitarianism. In the short run, such a diet may actually enhance the health of the person who follows the diet. (Warning: fruitarian diets are high-risk; consult a qualified health professional before undertaking a fruitarian diet for therapeutic purposes.)

However, in the long run, perhaps because the diet may be beyond the range of adaptation, undesired consequences can occur. In the case of fruitarianism, these consequences can include diabetes-like symptoms, severe emaciation, fatigue, mood swings, loss of libido, and serious mental consequences: life-controlling food obsessions, eating-disorder behaviors, incredibly hateful fanaticism, and so on. The loss of libido reported by many fruitarians (and some regular raw veg*ns) suggests that those who follow such a diet will fail to reproduce, and quickly die out in evolutionary terms. That explains one way that evolutionary selection pressure can quickly eliminate a discordant diet.

In contrast to the above real-world anecdotal experience, if following a fruitarian diet granted long-term robust health and increased sexual virility, it would enhance reproduction and thrive in the gene pool via survival of the fittest. Further, the enhanced reproduction inherent in such a diet would make such a diet predominant, over evolutionary time.

Side note: The above provides yet another argument against the claim that humans evolved as fruitarians. If the diet were even half as good as claimed, those who followed the diet (or the closest approximation thereof, per local conditions) would thrive and out-reproduce those on meat-based diets, and the fruitarian diet would have become the standard diet at some point in our evolution.

So, although an individual might adopt a discordant diet and benefit in the short run, unless the diet conveys--consistently--significant survival/reproduction advantages in the extant environment, the genes that support the diet will not survive to become "natural" or standard. Further, the data available to date (anecdotal data) does not support the idea that raw/veg*n diets convey a major survival advantage, in the long run.

Where is the credible, long-term longitudinal data on longevity for vegans vs. non-vegans? As Corder [1998, p. 130] observes, "Most of the literature which addresses diet and longevity is promotional, testimonial, observational or editorial." One wonders how many of the claims regarding veg*n longevity are promotional. It appears that many of the claims that veg*n diets promote longevity are based on short-term (cross-sectional) studies, and/or are extrapolations from studies that show trends toward better biomarkers (or lower disease rates) for people consuming more plant foods. The extrapolation of such studies from low levels of meat consumption to zero meat consumption is done at a considerably higher risk of statistical error, as such extrapolations go beyond the range of the data. Also, as mentioned previously, comparisons with the standard Western diet tell one nothing about likely comparisons with evolutionary or hunter-gatherer diets. (A further problem in comparing hunter-gatherer diets with veg*n diets is the low level of sanitation and high "occupational risks" of traditional hunter-gatherer lifestyles.)

Even more relevant here is the apparent paucity of long-term, longitudinal data on the longevity of strict, long-term vegans. Claims based on biomarkers are certainly of interest, but actual longevity data, collected over a long period, would be more credible. And of course, one needs other, supplementary data to properly analyze longevity, e.g., data on smoking, alcohol use, accidental deaths, etc. Until such long-term longitudinal data sets are available, claims of veg*n longevity may be subject to challenge. [Note: Readers are invited to contact the author with citations for long-term longitudinal studies of veg*n longevity.]

RATIONALIZATION:Hunter-gatherers may eat some meat but they are not that far from being vegetarians. Many raw/veg*n advocates say that: (a) hunter-gatherers usually have a diet in which plant foods are predominant, and also that (b) hunter-gatherers rarely hunt, and when they do they are usually unsuccessful. Ergo, their diet is nearly vegetarian. (Note: This general idea, in varying forms, is held not just by raw extremists, but tends to be shared by those who identify themselves as conventional vegans as well.)

REPLY:This claim can probably be traced back to early (since superseded) anthropological work on hunter-gatherers, and may also be based on a flawed and outdated hunter-gatherer survey interpretation. The claim is a false myth, and one that certain "diet gurus" (and, as well, more scientifically oriented conventional vegans who should probably know better) are quite happy to propagate.

Popularized early studies of San Bushmen as one source of the myth. The myth of the minimally-meat-eating hunter-gatherer may have its roots in early publicity surrounding one of the first well-studied hunter-gatherer societies to gain widespread attention (in the 1960s/1970s) in the anthropological community--the San tribes of the Kalahari Desert in Africa. In particular, the !Kung San, widely reported on as a mostly peaceful, egalitarian tribe who ate much more plant food than meat, went on to become something of a cause celebre as the prototype of hunter-gatherers--as well as a Rorschach blot for anyone with a theory about humanity's inborn sociocultural inclinations to utilize as a jumping-off point. (For an overview of early romanticism about the !Kung, and how knowledge and views of hunter-gatherers since then have grown and changed, see Lewin [1988].)

But as it was to happen, further research and analysis has since shown that the San are unrepresentative of the majority of hunter-gatherer tribes where plant-to-animal-food ratios are concerned. (The !Kung San derive 37% of their food from animal foods, the Kade San 20% [Eaton 1985]; and in this connection, it's worth remarking here that even 20% is a significant amount--in reality not really that close to being "nearly vegetarian.")

Flawed early survey of worldwide hunter-gatherers as another source. Richard Lee did some of the influential early (and still well-regarded) anthropological work studying the !Kung. (See Lee [1979] for a report of his anthropological observations.) However, it is not just the diet of the !Kung San or related Bushmen that may be the source of the widespread (erroneous) "mostly gatherer" view of pre-agricultural people, but perhaps also a hunter-gatherer survey of Lee [1968]. The survey of Lee did claim that hunter-gatherers gathered more than they hunted. However, as Ember [1978] explains, Lee's interpretation of the survey data (not the survey itself) was seriously flawed and unrepresentative of hunter-gatherers. The flaws in Lee's survey interpretation are as follows:

He reclassified shellfish-collecting as gathering, rather than hunting.

He (arbitrarily) excluded many North American hunter-gatherer tribes from the survey (which was based on the Ethnographic Atlas [Murdock 1967]). The result of this was, as described by Ember [1978], to arbitrarily increase the importance of gathering in the survey.

More recent and detailed analysis of survey data finds hunting more important than gathering. Ember [1978, table 2,p. 441] describes a more thorough survey utilizing all of the tribes in the Ethnographic Atlas (including the North American cases excluded by Lee), which found that in 77% of the hunter-gatherer societies, gathering contributed less than half the food calories. Hunting and gathering contributed approximately equal calories in 13% of the societies, and gathering contributed more calories than hunting in only 10% of the societies. (Also see the subsection on hunter-gatherers in "Metabolic Evidence of Human Adaptation to Increased Carnivory" on this website for an even more up-to-date analysis of the Ethnographic Atlas survey data being performed by researcher Loren Cordain's group that corroborates this assessment.)

Thus we note that the claim hunter-gatherers are incompetent hunters and rely primarily on gathering is false, and that hunter-gatherer societies where gathered plant food is a more important food source than hunting are a very small minority.

Outdated, incorrect claims that Australian Aborigines were "nearly vegetarian." The San Bushmen are not the only hunter-gatherer group whose diet has been misunderstood or misrepresented. One can also find inaccurate claims that the Aborigines of Australia were predominantly vegetarian. Lee [1996, p. 7] summarizes the situation nicely:

For many years it was believed that the Aboriginal diet was predominately vegetarian, and a statement that the central Australian desert diet was composed of "70-80% plant foods" [93] had been widely accepted [87, 101-103]. This is no longer believed to be the case. Meggitt [93] compared foods by estimated weight, which probably overassessed the importance of the vegetable component of the diet. Support for the vegetarian basis of the traditional desert diet had also been interpreted from botanical lists, observations illustrating the ripening of different plant food species throughout the year [96] and evidence of storage of plant foods. However, none of these sources attempted to quantify actual dietary intake, and the effects of climate, seasonality and specific location must also be considered [37, 70, 96]...

There is increasing evidence that both tropical savanna/coastal and desert [86, 90] diets were meat-oriented; vegetable foods provided an important supplement, rather than an alternative to animal foods, with proportions changing throughout the seasons [10, 25, 36, 82, 84, 100]. For example, the coastal people of Cape York concentrated so much on the procurement of marine mammals that vegetable foods were considered a luxury [7]. Desert Aborigines have described themselves specifically as meat eaters [106]. Early observers commented on the intake of meat of smaller mammals as a "mainstay" of the diet of central Australian tribes [80].

The above also reminds us to be cautious in evaluating earlier studies, and to use all the available evidence when evaluating the diets of hunter-gatherers. Otherwise, one may end up making fallacious claims, as here, e.g., that Australian Aborigines (or other hunter-gatherers) were "nearly vegetarian."

RATIONALIZATION:There are no vegan gatherer tribes because they have not been exposed to the "enlightened" philosophy of veg*nism. They are living in ignorance and have not evolved spiritually.

REPLY:That there are no vegan hunter-gatherer tribes suggests the diet is neither feasible for them nor natural. Stop and think carefully about the nature of claims that a particular diet somehow makes you "enlightened" or "superior." Stripped of their idealistic rhetoric, the nature of such claims is, quite simply: "My lunch is better than yours, and that makes me a better person than you!" Even worse, a few fruitarian extremists actively promote this nonsense in dishonest and incredibly hateful ways. I hope that you can see that rather than "enlightened," such attitudes are really self-righteous, egotistical, and the dietary equivalent of racism. Because of this, it is best to not view veg*n philosophy as "enlightened."

RATIONALIZATION:The hunter-gatherer diet is not feasible for people living in modern times; it's just a bunch of academic "ivory-tower" theorizing about diet and nutrition. Vegan diets are real and work!

REPLY:The earlier section regarding FTT (failure to thrive) indicates that veg*n diets don't seem to work for everyone. As for the claim that hunter-gatherer diets are all academic, a partially tongue-in-cheek reply here is: Whether paleodiets are fully achievable in today's world at this point might be debated--however, is it not obvious that attempts to approximate them will certainly be much closer than attempts not to? More seriously, the section Should You Eat Meat? (later herein) briefly describes how it may be possible to approximate a hunter-gatherer diet today.